We present chemical abundance measurements for seven stars with metallicities ranging from [ Fe/H ] = - 3.3 to [ Fe/H ] = - 2.4 in the Tucana II ultra-faint dwarf galaxy ( UFD ) , based on high-resolution spectra obtained with the MIKE spectrograph on the 6.5 m Magellan-Clay Telescope .
For three stars , we present detailed chemical abundances for the first time .
Of those , two stars are newly discovered members of Tucana II and were selected as probable members from deep narrow band photometry of the Tucana II UFD taken with the SkyMapper telescope .
This result demonstrates the potential for photometrically identifying members of dwarf galaxy systems based on chemical composition .
One new star was selected from the membership catalog of \citet wmo+16 .
The other four stars in our sample have been re-analyzed , following additional observations .
Overall , six stars have chemical abundances that are characteristic of the UFD stellar population .
The seventh star shows chemical abundances that are discrepant from the other Tucana II members and an atypical , higher strontium abundance than what is expected for typical UFD stars .
While unlikely , its strontium abundance raises the possibility that it may be a foreground metal-poor halo star with the same systemic velocity as Tucana II .
If we were to exclude this star , Tucana II would satisfy the criteria to be a surviving first galaxy .
Otherwise , this star implies that Tucana II has likely experienced somewhat extended chemical evolution .